Development of a Precast Bridge Deck Overhang System

Prestressed-precast panels are commonly used at interior beams for bridge decks in Texas. The use of these panels can provide ease of construction, sufficient capacity, and good economy for the construction of bridge decks in Texas. Current practice for the overhang deck sections require that formwork be constructed at the outer edges of the bridge. The cost of constructing the bridge overhang is significantly higher than that of the interior sections where precast panels are used. The development of a precast overhang system has the potential to improve economy and safety in bridge construction. This research investigated the overhang and shear capacity of a precast overhang system for potential use during the construction of bridges with precast overhang panels. The research was performed in three phases: the Phase 1 research including work specifically for the Rock Creek Bridge in Parker County, Texas; the Phase 2 research for general precast overhang panels, and; the Phase 3 research investigating the shear capacity. Grout material characteristics were also assessed for possible use in the haunch; constructability issues were also addressed. Results indicate that the capacity of the precast overhang system is sufficient to carry factored AASHTO loads with no or very limited cracking. Results from the shear study indicate that the shear capacity of threaded rods with couplers is lower than the conventional R-bar system. However, sufficient shear capacity can be achieved if sufficient pockets in the precast overhang panel are provided. A recommendation for the haunch form system for use on the bridge is also provided. The use of the precast overhang system evaluated can be implemented in bridge construction. However, further testing is needed to determine the number of pockets on the overhang panel--an issue critical to the constructability and economy of the system. This will be further addressed in report 0-6100-3.